SpCas9 Nuclease

Product Introduction

SpCas9 Nuclease (Streptococcus pyogenes Cas9), derived from Streptococcus pyogenes, is the most representative RNA-guided DNA endonuclease within the CRISPR-Cas system and is currently the most widely used nuclease in the field of gene editing. This protein has a molecular weight of approximately 160 kDa and consists of 1368 amino acids. It features a unique bilobal architecture: the recognition (REC) lobe is responsible for binding the single-guide RNA (sgRNA) and the target DNA, while the nuclease (NUC) lobe contains two catalytic domains, HNH and RuvC, which cleave the target strand complementary to the sgRNA and the non-complementary strand, respectively. This structural design enables SpCas9, under the precise guidance of sgRNA, to locate specific genomic sites by recognizing the NGG protospacer adjacent motif (PAM) sequence, introducing a blunt-ended DNA double-strand break (DSB) approximately 3 bp upstream of the PAM. Subsequently, the cell repairs the break through two primary DNA repair pathways—non-homologous end joining (NHEJ) or homology-directed repair (HDR)—thereby achieving gene knockout, knock-in, or precise editing.

The widespread application of SpCas9 is attributed to its high editing efficiency, simplicity of target design, and powerful programmability. However, its dependence on the NGG PAM sequence somewhat limits its targeting range and may lead to off-target effects. To address this, researchers have developed various SpCas9 variants, such as high-fidelity SpCas9 (SpCas9-HF) and enhanced SpCas9 (eSpCas9), to improve specificity or expand PAM recognition capabilities. Furthermore, SpCas9 is extensively utilized in basic research, gene therapy, crop improvement, and other fields, driving rapid advancements in life sciences and medicine.